This application relates to a method and system for adjusting the position of the zone dampers in a multi-zone heating, ventilating and air conditioning (HVAC) system to ensure that unduly high levels of air do not flow into any of the zones.
Multi-zone HVAC systems are known, and include a component(s) for changing the temperature and condition of air (a furnace, air conditioner, heat pump, etc.). For simplicity, these components will be referred to collectively as a temperature changing component. Also, an indoor air handler drives air from the temperature changing component through supply ducts to several zones within a building. Each of the supply ducts typically has dampers that may be controlled to restrict or allow flow of air into each zone to achieve a desired temperature.
The air handler is delivering a fixed amount of air under most operational conditions, and that air is divided between the several zones based upon the damper position, and the size of each duct relative to the other ducts. As one of the dampers is closed, additional air will be driven through the other supply ducts having an open damper. At times, this may cause the amount of air flowing into any one zone to become higher than would be desirable. The damper positions are selected to achieve a desired temperature in that zone, and if additional air is driven through the supply duct into a zone, typically, that zone may become over-conditioned.
In addition, as the amount of air flowing into any one zone increases, the noise level in that zone also increases. At times, this noise level may become undesirably high.
Typically, the prior art has included a pressure responsive bypass for allowing excess air to be returned to the supply or return duct and back to the temperature changing component. This bypass puts an upper limit on the amount of air that may flow into any zone. This solution, however, requires the expense and installation of a bypass valve. Further, by returning already conditioned air to the return duct, the air reaching the temperature changing component is not at the temperature which would be expected from ambient air. As such, additional problems can arise.